This invention relates generally to sensor systems and, more particularly, to sensor systems for determining the rotation of shafts and axles for vehicles and other applications.
Antilock braking systems and traction control systems are now commonplace in the automotive marketplace and are standard equipment on many car models. The basis of these systems is a sensor system that senses wheel speed or rotation and relays that information to a controller. The controller dictates, for example, the application of braking force intermittently to keep a respective wheel from skidding or slipping. Such use of the braking system allows vehicles to remain in control during maximum braking and to stop more efficiently. Similarly, controllers can dictate the application of driving force for optimum traction.
Current sensor systems for antilock brakes and traction control are of three types: 1) non-integrated variable reluctance type, 2) integrated hub assembly type, and 3) integrated spindle sensor bearing type. Non-integrated variable reluctance sensors often require adjustment after installation. Integrated hub assembly units require a large number of individual parts, introducing problems relating to inventory, installation and serviceability of those parts. Integrated spindle sensor bearings can limit an automotive manufacturer to a single supplier and may require new bearing designs to incorporate the sensor and encoder.
The foregoing illustrates limitations known to exist in present sensor systems for antilock brakes and the like. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.